New Username

As You all know, my old username was TheBlueKnight9, But I changed it lastnight! I am woundering when I will be able to change it again (back to TheBlueKnight9) Because it will not allow me to do so! I have a friend who has changed his username three times, and hope you could help tell me when it will let me do so again.

Thanks for reading this and hopfully helping me!